1. Field of the Invention
The present invention relates generally to electrophoresis gel assemblies and to methods of making an electrophoresis gel.
2. Related Art
Electrophoresis gels are use routinely in laboratories for the separation and analysis of proteins, poly-nucleic acids (such as DNA and RNA) and carbohydrates. The gels are typically uniformly transparent. They contain a sample loading area, such as holes in gels run horizontally or sample pockets in gels run vertically. These sample pockets are typically formed using a comb-shaped device inserted into the top of the mold when forming the gel. Because the gel is transparent and has about the same refractive index as the solutions used to fill the wells before loading samples onto them, it is difficult to see where the wells actually are. The smaller the sample wells, the more challenging it is to actually load samples in the correct place. Further, since samples are usually loaded near the bottom of the sample well using pipettes, knowing where the bottom of the well is would be useful.
Some improvements to gels have been made to improve loading. For example, U.S. Pat. No. 5,656,145 issued to Nguyen uses a loading guide so one can direct the samples into the wells without seeing them. Pre-cast gel products are also made with an outline printed on the outside of the mold in which the gel is contained, showing where the wells are supposed to be. These methods are cumbersome or imprecise, and complicated by the fact that the gel fingers dividing the wells may move. Other efforts have been made using visible or fluorescent soluble dyes in the loading area. These dyes tend to diffuse out of the loading area, may migrate down the gels during electrophoresis, or bleach out of the gel during polymerization (especially photo-polymerization). Finally, alternate structures, such as plastic ribs or walls have been used to divide sample-loading wells, making them easier to see. Examples of these can be found in U.S. Pat. No. 6,878,257 to Manusu and U.S. Patent application 20030141190 by Alpenfels. While useful, these structures are more expensive to make, can inhibit polymerization of the gel fingers, and can block the current flow, which in turn causes samples separated in adjacent lanes to merge together. Further, since samples are usually loaded near the bottom of the sample well using pipettes, knowing where the bottom of the well is would be useful. If one tries to expel sample from the pipette into the well while it is touching the top of the gel surface, the sample expels with too much force when the pipette is raised, often ruining the quality of the resulting separation. None of the prior art helps to know such information with certainty.